Should the IAC's only be affected by the "Idle Air Control" and "Idle Air" tabs of LS1 Edit? If so, which way should I should I adjust them to start seeing lower IAC counts. I get slight surging from time to time....and no I dont want to drill the TB....I know there has to be a way to just make the IAC motor open more or less or something like that....Any ideas...?

 

Here's the simple but not very well known way.

Turn your idle stop screw until your TPS reads 2-3 degrees higher than before on Autotap.
Unplug your TPS with the ignition off.
Turn the ignition on.
Plug the TPS back in.
Your TPS should now show 0. If not, turn the ignition off then back on (going by memory here.)
Your IACs will now be lower. If they're close to zero then you went too far.

 

thats a cool way to do it, although wouldnt that raise the idle RPM too? I have the idle set aroun 850 right now. I want it to lope more. With EFI Live, I got it down to 650 tonight, and it sounded awesome...I remember when I first installed the cam, it was idleing on the stock 550 RPM, and sounded sweet, although it did surge a bit....I might just try that way out...

 

So this works all the time and you do not have drill your TB. Sounds too easy. When you ATAP your car do you want your IAC to be zero. I read that somewhere that 20-30 was exceptable.

 

What's wrong with drilling the TB? I still had to drill mine even with tuning to get it to idle as stable as I wanted at the rpm I wanted....

 

There's nothing wrong with drilling the TB.

NO, it will not raise the idle. Instead, it will lower the IACs. All the IAC does is allow in extra air to maintain the idle. We're just changing it's starting point.

This is doing THE EXACT same thing as drilling the TB hole. It's simply letting in more air.

You DO NOT want your IACs to be at zero. This will throw a code. ~20-40 is good with the engine fully warmed. Check it with the tranny in gear and in neutral, with the AC on with it off. Make sure the minimum IAC is above zero...and remember, your IACs will change a bit with atmospheric conditions so allow some safety margin. This is why I say 20-40.

The only reason more people don't do this is because they don't know they can. I just happened upon this through messing with my car. I've never heard anyone else suggest this.

 

thats cool, I might just give it a try tonight...So what will adjusting those 2 tabs I mentioned earlier with EDIT do....?

 

Colonel: I recently discovered this little trick too. Works very well on Fbodys and trucks. Nice thread..........

Richard

 

Ok, I did it last night, and it seemed to help out quite a bit. The IACS were over 100 before...now they are down to 20-40. I ended up taking the TB completely off, and taking the idle stop screw totally out, and turning it over. Why the hell would GM put the head of it on the bottom...Oh well. It works now, and is not a lot easier to adjust....

Now if I can just figure out these startup issues...

 

Good information. I did this yesterday to get my IACs in order. On my 2000, the screw for the throttle stop is a T-15 Torx... A 1/4" ratchet and T-15 socket make it easy to adjust from the bottom. Matt

 

im gonna have to try this also

 

im gonna have to try this also

 

Quote:

Originally Posted by JxxxOxxxE

Ok, I did it last night, and it seemed to help out quite a bit. The IACS were over 100 before...now they are down to 20-40. I ended up taking the TB completely off, and taking the idle stop screw totally out, and turning it over. Why the hell would GM put the head of it on the bottom...Oh well. It works now, and is not a lot easier to adjust....

That is exactly what I did when I installed my cam. Works great.

 

this is a stupid question, but where is the screw at? i looked for it but couldnt find it. and what should i be looking for on the A-tap to raise by 2-3 ?

thanks guys

 

the screw should be in the tab that is basically what stops the TB on the return. You chould look for the throttle position sensor to be 2% higher...I had to do what Colonel said above, then turn the car off once or twice....After pluggin the sensor back it, it read like 15.3% until turning it off and on a time or 2...